America's 20 largest corporate giants

Wal-Mart Stores, a multinational retailer runs large discount department stores and warehouse stores across the world.

It is also the biggest private employer in the world with over two million employees, and is the largest retailer in the world. Walmart remains a family-owned business, as the company is controlled by the Walton family who own a 48% stake in Walmart. The company was founded by Sam Walton in 1962.

America's 20 largest corporate giants

ConocoPhillips Company is the fifth largest private sector energy corporation in the world and one of the six 'supermajor' oil companies.

It sells fuel under the Conoco, Phillips 66 and Union 76 brands in North America, and Jet in Europe. ConocoPhillips was created through the merger of Conoco Inc and the Phillips Petroleum Company on August 30, 2002.

America's 20 largest corporate giants

Berkshire Hathaway and its subsidiaries engage in diverse business activities including property and casualty insurance and reinsurance, utilities and energy, freight rail transportation, finance, manufacturing, retailing and services.

America's 20 largest corporate giants

World's leading PC manufacturer, Hewlett-Packard provides products, technologies, software, solutions and services to consumers, small- and medium-sized businesses (SMBs) and large enterprises, including customers in the government, health and education sectors.

The company was founded in a garage in Palo Alto by William (Bill) Redington Hewlett and Dave Packard.

America's 20 largest corporate giants

McKesson Corporation is the largest pharmaceuticals company in the world, which provides medicines, pharmaceutical supplies, information and care management products and services across the healthcare industry.

Founded in New York City as Olcott & McKesson by Charles Olcott and John McKesson in 1833, it is the 15th largest company in the United States.